jdk/src/share/classes/java/time/Month.java
changeset 15289 3ac550392e43
child 15658 55b829ca2334
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/time/Month.java	Tue Jan 22 20:59:21 2013 -0800
@@ -0,0 +1,608 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ *  * Neither the name of JSR-310 nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package java.time;
+
+import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
+import static java.time.temporal.ChronoUnit.MONTHS;
+
+import java.time.format.DateTimeFormatterBuilder;
+import java.time.format.TextStyle;
+import java.time.temporal.Chrono;
+import java.time.temporal.ChronoField;
+import java.time.temporal.ISOChrono;
+import java.time.temporal.Queries;
+import java.time.temporal.Temporal;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.TemporalAdjuster;
+import java.time.temporal.TemporalField;
+import java.time.temporal.TemporalQuery;
+import java.time.temporal.ValueRange;
+import java.util.Locale;
+
+/**
+ * A month-of-year, such as 'July'.
+ * <p>
+ * {@code Month} is an enum representing the 12 months of the year -
+ * January, February, March, April, May, June, July, August, September, October,
+ * November and December.
+ * <p>
+ * In addition to the textual enum name, each month-of-year has an {@code int} value.
+ * The {@code int} value follows normal usage and the ISO-8601 standard,
+ * from 1 (January) to 12 (December). It is recommended that applications use the enum
+ * rather than the {@code int} value to ensure code clarity.
+ * <p>
+ * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code Month}.
+ * Use {@code getValue()} instead.</b>
+ * <p>
+ * This enum represents a common concept that is found in many calendar systems.
+ * As such, this enum may be used by any calendar system that has the month-of-year
+ * concept defined exactly equivalent to the ISO-8601 calendar system.
+ *
+ * <h3>Specification for implementors</h3>
+ * This is an immutable and thread-safe enum.
+ *
+ * @since 1.8
+ */
+public enum Month implements TemporalAccessor, TemporalAdjuster {
+
+    /**
+     * The singleton instance for the month of January with 31 days.
+     * This has the numeric value of {@code 1}.
+     */
+    JANUARY,
+    /**
+     * The singleton instance for the month of February with 28 days, or 29 in a leap year.
+     * This has the numeric value of {@code 2}.
+     */
+    FEBRUARY,
+    /**
+     * The singleton instance for the month of March with 31 days.
+     * This has the numeric value of {@code 3}.
+     */
+    MARCH,
+    /**
+     * The singleton instance for the month of April with 30 days.
+     * This has the numeric value of {@code 4}.
+     */
+    APRIL,
+    /**
+     * The singleton instance for the month of May with 31 days.
+     * This has the numeric value of {@code 5}.
+     */
+    MAY,
+    /**
+     * The singleton instance for the month of June with 30 days.
+     * This has the numeric value of {@code 6}.
+     */
+    JUNE,
+    /**
+     * The singleton instance for the month of July with 31 days.
+     * This has the numeric value of {@code 7}.
+     */
+    JULY,
+    /**
+     * The singleton instance for the month of August with 31 days.
+     * This has the numeric value of {@code 8}.
+     */
+    AUGUST,
+    /**
+     * The singleton instance for the month of September with 30 days.
+     * This has the numeric value of {@code 9}.
+     */
+    SEPTEMBER,
+    /**
+     * The singleton instance for the month of October with 31 days.
+     * This has the numeric value of {@code 10}.
+     */
+    OCTOBER,
+    /**
+     * The singleton instance for the month of November with 30 days.
+     * This has the numeric value of {@code 11}.
+     */
+    NOVEMBER,
+    /**
+     * The singleton instance for the month of December with 31 days.
+     * This has the numeric value of {@code 12}.
+     */
+    DECEMBER;
+    /**
+     * Private cache of all the constants.
+     */
+    private static final Month[] ENUMS = Month.values();
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code Month} from an {@code int} value.
+     * <p>
+     * {@code Month} is an enum representing the 12 months of the year.
+     * This factory allows the enum to be obtained from the {@code int} value.
+     * The {@code int} value follows the ISO-8601 standard, from 1 (January) to 12 (December).
+     *
+     * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
+     * @return the month-of-year, not null
+     * @throws DateTimeException if the month-of-year is invalid
+     */
+    public static Month of(int month) {
+        if (month < 1 || month > 12) {
+            throw new DateTimeException("Invalid value for MonthOfYear: " + month);
+        }
+        return ENUMS[month - 1];
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Obtains an instance of {@code Month} from a temporal object.
+     * <p>
+     * A {@code TemporalAccessor} represents some form of date and time information.
+     * This factory converts the arbitrary temporal object to an instance of {@code Month}.
+     * <p>
+     * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} field.
+     * The extraction is only permitted if the temporal object has an ISO
+     * chronology, or can be converted to a {@code LocalDate}.
+     * <p>
+     * This method matches the signature of the functional interface {@link TemporalQuery}
+     * allowing it to be used in queries via method reference, {@code Month::from}.
+     *
+     * @param temporal  the temporal object to convert, not null
+     * @return the month-of-year, not null
+     * @throws DateTimeException if unable to convert to a {@code Month}
+     */
+    public static Month from(TemporalAccessor temporal) {
+        if (temporal instanceof Month) {
+            return (Month) temporal;
+        }
+        try {
+            if (ISOChrono.INSTANCE.equals(Chrono.from(temporal)) == false) {
+                temporal = LocalDate.from(temporal);
+            }
+            return of(temporal.get(MONTH_OF_YEAR));
+        } catch (DateTimeException ex) {
+            throw new DateTimeException("Unable to obtain Month from TemporalAccessor: " + temporal.getClass(), ex);
+        }
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the month-of-year {@code int} value.
+     * <p>
+     * The values are numbered following the ISO-8601 standard,
+     * from 1 (January) to 12 (December).
+     *
+     * @return the month-of-year, from 1 (January) to 12 (December)
+     */
+    public int getValue() {
+        return ordinal() + 1;
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the textual representation, such as 'Jan' or 'December'.
+     * <p>
+     * This returns the textual name used to identify the month-of-year.
+     * The parameters control the length of the returned text and the locale.
+     * <p>
+     * If no textual mapping is found then the {@link #getValue() numeric value} is returned.
+     *
+     * @param style  the length of the text required, not null
+     * @param locale  the locale to use, not null
+     * @return the text value of the month-of-year, not null
+     */
+    public String getText(TextStyle style, Locale locale) {
+        return new DateTimeFormatterBuilder().appendText(MONTH_OF_YEAR, style).toFormatter(locale).print(this);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Checks if the specified field is supported.
+     * <p>
+     * This checks if this month-of-year can be queried for the specified field.
+     * If false, then calling the {@link #range(TemporalField) range} and
+     * {@link #get(TemporalField) get} methods will throw an exception.
+     * <p>
+     * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then
+     * this method returns true.
+     * All other {@code ChronoField} instances will return false.
+     * <p>
+     * If the field is not a {@code ChronoField}, then the result of this method
+     * is obtained by invoking {@code TemporalField.doIsSupported(TemporalAccessor)}
+     * passing {@code this} as the argument.
+     * Whether the field is supported is determined by the field.
+     *
+     * @param field  the field to check, null returns false
+     * @return true if the field is supported on this month-of-year, false if not
+     */
+    @Override
+    public boolean isSupported(TemporalField field) {
+        if (field instanceof ChronoField) {
+            return field == MONTH_OF_YEAR;
+        }
+        return field != null && field.doIsSupported(this);
+    }
+
+    /**
+     * Gets the range of valid values for the specified field.
+     * <p>
+     * The range object expresses the minimum and maximum valid values for a field.
+     * This month is used to enhance the accuracy of the returned range.
+     * If it is not possible to return the range, because the field is not supported
+     * or for some other reason, an exception is thrown.
+     * <p>
+     * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
+     * range of the month-of-year, from 1 to 12, will be returned.
+     * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
+     * <p>
+     * If the field is not a {@code ChronoField}, then the result of this method
+     * is obtained by invoking {@code TemporalField.doRange(TemporalAccessor)}
+     * passing {@code this} as the argument.
+     * Whether the range can be obtained is determined by the field.
+     *
+     * @param field  the field to query the range for, not null
+     * @return the range of valid values for the field, not null
+     * @throws DateTimeException if the range for the field cannot be obtained
+     */
+    @Override
+    public ValueRange range(TemporalField field) {
+        if (field == MONTH_OF_YEAR) {
+            return field.range();
+        }
+        return TemporalAccessor.super.range(field);
+    }
+
+    /**
+     * Gets the value of the specified field from this month-of-year as an {@code int}.
+     * <p>
+     * This queries this month for the value for the specified field.
+     * The returned value will always be within the valid range of values for the field.
+     * If it is not possible to return the value, because the field is not supported
+     * or for some other reason, an exception is thrown.
+     * <p>
+     * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
+     * value of the month-of-year, from 1 to 12, will be returned.
+     * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
+     * <p>
+     * If the field is not a {@code ChronoField}, then the result of this method
+     * is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)}
+     * passing {@code this} as the argument. Whether the value can be obtained,
+     * and what the value represents, is determined by the field.
+     *
+     * @param field  the field to get, not null
+     * @return the value for the field, within the valid range of values
+     * @throws DateTimeException if a value for the field cannot be obtained
+     * @throws DateTimeException if the range of valid values for the field exceeds an {@code int}
+     * @throws DateTimeException if the value is outside the range of valid values for the field
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public int get(TemporalField field) {
+        if (field == MONTH_OF_YEAR) {
+            return getValue();
+        }
+        return TemporalAccessor.super.get(field);
+    }
+
+    /**
+     * Gets the value of the specified field from this month-of-year as a {@code long}.
+     * <p>
+     * This queries this month for the value for the specified field.
+     * If it is not possible to return the value, because the field is not supported
+     * or for some other reason, an exception is thrown.
+     * <p>
+     * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
+     * value of the month-of-year, from 1 to 12, will be returned.
+     * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
+     * <p>
+     * If the field is not a {@code ChronoField}, then the result of this method
+     * is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)}
+     * passing {@code this} as the argument. Whether the value can be obtained,
+     * and what the value represents, is determined by the field.
+     *
+     * @param field  the field to get, not null
+     * @return the value for the field
+     * @throws DateTimeException if a value for the field cannot be obtained
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public long getLong(TemporalField field) {
+        if (field == MONTH_OF_YEAR) {
+            return getValue();
+        } else if (field instanceof ChronoField) {
+            throw new DateTimeException("Unsupported field: " + field.getName());
+        }
+        return field.doGet(this);
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns the month-of-year that is the specified number of quarters after this one.
+     * <p>
+     * The calculation rolls around the end of the year from December to January.
+     * The specified period may be negative.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param months  the months to add, positive or negative
+     * @return the resulting month, not null
+     */
+    public Month plus(long months) {
+        int amount = (int) (months % 12);
+        return ENUMS[(ordinal() + (amount + 12)) % 12];
+    }
+
+    /**
+     * Returns the month-of-year that is the specified number of months before this one.
+     * <p>
+     * The calculation rolls around the start of the year from January to December.
+     * The specified period may be negative.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param months  the months to subtract, positive or negative
+     * @return the resulting month, not null
+     */
+    public Month minus(long months) {
+        return plus(-(months % 12));
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the length of this month in days.
+     * <p>
+     * This takes a flag to determine whether to return the length for a leap year or not.
+     * <p>
+     * February has 28 days in a standard year and 29 days in a leap year.
+     * April, June, September and November have 30 days.
+     * All other months have 31 days.
+     *
+     * @param leapYear  true if the length is required for a leap year
+     * @return the length of this month in days, from 28 to 31
+     */
+    public int length(boolean leapYear) {
+        switch (this) {
+            case FEBRUARY:
+                return (leapYear ? 29 : 28);
+            case APRIL:
+            case JUNE:
+            case SEPTEMBER:
+            case NOVEMBER:
+                return 30;
+            default:
+                return 31;
+        }
+    }
+
+    /**
+     * Gets the minimum length of this month in days.
+     * <p>
+     * February has a minimum length of 28 days.
+     * April, June, September and November have 30 days.
+     * All other months have 31 days.
+     *
+     * @return the minimum length of this month in days, from 28 to 31
+     */
+    public int minLength() {
+        switch (this) {
+            case FEBRUARY:
+                return 28;
+            case APRIL:
+            case JUNE:
+            case SEPTEMBER:
+            case NOVEMBER:
+                return 30;
+            default:
+                return 31;
+        }
+    }
+
+    /**
+     * Gets the maximum length of this month in days.
+     * <p>
+     * February has a maximum length of 29 days.
+     * April, June, September and November have 30 days.
+     * All other months have 31 days.
+     *
+     * @return the maximum length of this month in days, from 29 to 31
+     */
+    public int maxLength() {
+        switch (this) {
+            case FEBRUARY:
+                return 29;
+            case APRIL:
+            case JUNE:
+            case SEPTEMBER:
+            case NOVEMBER:
+                return 30;
+            default:
+                return 31;
+        }
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the day-of-year corresponding to the first day of this month.
+     * <p>
+     * This returns the day-of-year that this month begins on, using the leap
+     * year flag to determine the length of February.
+     *
+     * @param leapYear  true if the length is required for a leap year
+     * @return the day of year corresponding to the first day of this month, from 1 to 336
+     */
+    public int firstDayOfYear(boolean leapYear) {
+        int leap = leapYear ? 1 : 0;
+        switch (this) {
+            case JANUARY:
+                return 1;
+            case FEBRUARY:
+                return 32;
+            case MARCH:
+                return 60 + leap;
+            case APRIL:
+                return 91 + leap;
+            case MAY:
+                return 121 + leap;
+            case JUNE:
+                return 152 + leap;
+            case JULY:
+                return 182 + leap;
+            case AUGUST:
+                return 213 + leap;
+            case SEPTEMBER:
+                return 244 + leap;
+            case OCTOBER:
+                return 274 + leap;
+            case NOVEMBER:
+                return 305 + leap;
+            case DECEMBER:
+            default:
+                return 335 + leap;
+        }
+    }
+
+    /**
+     * Gets the month corresponding to the first month of this quarter.
+     * <p>
+     * The year can be divided into four quarters.
+     * This method returns the first month of the quarter for the base month.
+     * January, February and March return January.
+     * April, May and June return April.
+     * July, August and September return July.
+     * October, November and December return October.
+     *
+     * @return the first month of the quarter corresponding to this month, not null
+     */
+    public Month firstMonthOfQuarter() {
+        return ENUMS[(ordinal() / 3) * 3];
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Queries this month-of-year using the specified query.
+     * <p>
+     * This queries this month-of-year using the specified query strategy object.
+     * The {@code TemporalQuery} object defines the logic to be used to
+     * obtain the result. Read the documentation of the query to understand
+     * what the result of this method will be.
+     * <p>
+     * The result of this method is obtained by invoking the
+     * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
+     * specified query passing {@code this} as the argument.
+     *
+     * @param <R> the type of the result
+     * @param query  the query to invoke, not null
+     * @return the query result, null may be returned (defined by the query)
+     * @throws DateTimeException if unable to query (defined by the query)
+     * @throws ArithmeticException if numeric overflow occurs (defined by the query)
+     */
+    @SuppressWarnings("unchecked")
+    @Override
+    public <R> R query(TemporalQuery<R> query) {
+        if (query == Queries.chrono()) {
+            return (R) ISOChrono.INSTANCE;
+        } else if (query == Queries.precision()) {
+            return (R) MONTHS;
+        }
+        return TemporalAccessor.super.query(query);
+    }
+
+    /**
+     * Adjusts the specified temporal object to have this month-of-year.
+     * <p>
+     * This returns a temporal object of the same observable type as the input
+     * with the month-of-year changed to be the same as this.
+     * <p>
+     * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
+     * passing {@link ChronoField#MONTH_OF_YEAR} as the field.
+     * If the specified temporal object does not use the ISO calendar system then
+     * a {@code DateTimeException} is thrown.
+     * <p>
+     * In most cases, it is clearer to reverse the calling pattern by using
+     * {@link Temporal#with(TemporalAdjuster)}:
+     * <pre>
+     *   // these two lines are equivalent, but the second approach is recommended
+     *   temporal = thisMonth.adjustInto(temporal);
+     *   temporal = temporal.with(thisMonth);
+     * </pre>
+     * <p>
+     * For example, given a date in May, the following are output:
+     * <pre>
+     *   dateInMay.with(JANUARY);    // four months earlier
+     *   dateInMay.with(APRIL);      // one months earlier
+     *   dateInMay.with(MAY);        // same date
+     *   dateInMay.with(JUNE);       // one month later
+     *   dateInMay.with(DECEMBER);   // seven months later
+     * </pre>
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param temporal  the target object to be adjusted, not null
+     * @return the adjusted object, not null
+     * @throws DateTimeException if unable to make the adjustment
+     * @throws ArithmeticException if numeric overflow occurs
+     */
+    @Override
+    public Temporal adjustInto(Temporal temporal) {
+        if (Chrono.from(temporal).equals(ISOChrono.INSTANCE) == false) {
+            throw new DateTimeException("Adjustment only supported on ISO date-time");
+        }
+        return temporal.with(MONTH_OF_YEAR, getValue());
+    }
+
+}